It was pretty bad for me as well when I first flashed, and usage showed 35-60% of it was the screen usage. I just reset the battery by draining it completely, charging for 8 hours on, turn off and charge for an hour, turn on unplugged for 2 minutes then turn off and charge for another hour and my battery life is much better. It still seems a bit less than GB, but part of it may be due to juice defender not being able to do as much (only shows 1.5x where it used to show 2.5x).
Motorola Droid Razr XT912
Asus Transformer TF101